What creates noticeable defects on digital imagers?

Hot pixels are defects that are permanent in nature and develop during the camera's lifetime. A common misconception is that a small number of hot pixels will not significantly deteriorate the image quality. In this thesis we show that the accumulating hot pixels will result in image degradation and this increases as pixel shrinks and sensitivity gains. This occurs because the camera's demosaicing and JPEG compression algorithms expand the damage area of each single defect. Worse, two hot pixels within a 5×5 pixel area spread the damage widely and yet are surprisingly probable events. We developed both analytical (birthday problem) and Monte Carlo simulations to estimate the number of hot pixels required to achieve a given probability of having two defective pixels occur in a 5×5 square. Finally, we performed a perceptual assessment to evaluate how detectable the hot pixel degradation is to human eyes in a sequence of images.